It was unclear how the fire was started. Some Afghan media reported that insurgents had fired rockets at the tankers late on Friday. There were no immediate reports of casualties.

"The number of tankers on fire is not yet clear, but based on preliminary reports from police around 200 tankers have been burnt," the interior ministry said in a statement.

The attack happened as Afghanistan prepares to announce preliminary results of the final round of a presidential election on Monday in a tense atmosphere. Each of the two candidates vying to succeed President Hamid Karzai accuses the other of mass fraud.

The Taliban have vowed to disrupt the election process. On Thursday, militants fired rockets into Kabul's international airport, destroying a helicopter.